Rain-Bird makes a rain detector that I use on my sprinkler system. This is a made up of a small open top container (1.5"x1.5"x .5" deep) with two probes that stick down into the container. It has some built-in electronics. The way it works is simple. All the valves on the system have a common lead to which they are all tied together. The rain-detector goes between the controller and the valves common lead. When there has been sufficient rain fall to cause there to be enough water in the container to touch both probes, the circuit between the controller and the valves is opened. The controller will go ahead and try to turn on the valves at the appointed time, but with the common line open, there is no return path and the valve stays off. The water in the container will eventually evaporate enough to not be touching both probes, allowing the valves to work again. Cost was ~$30 at Home Depot. David V. Fansler Network Administrator AutoCyte, Inc. 336-222-9707 Ext. 261 dfansler@autocyte.com Now Showing! www.mindspring.com/~dfansler Updated July 13, 1999 -----Original Message----- From: John Waters [mailto:john_fm_waters@HOTMAIL.COM] Sent: Thursday, August 26, 1999 12:41 PM To: PICLIST@MITVMA.MIT.EDU Subject: [OT] Rain Detection Hi All, I have built an automated lawn spraying system for my backyard. A PC is used to turn ON and OFF the water valve periodically according to a preset schedule. The problem now is, it may sometimes be raining during, or shortly before the spray time, which would simply waste water. Is there any commerically available rainfall detector that could be interface to my PC? I want to use it to stop unnecessary spraying. Or, I could build my own circuit for doing this, does anyone get such a circuit? Thanks in advance John ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com